Drilling in bones, particularly bones of the face and head, requires accurate and reliable control over the penetration depth. For instance, over drilling and tapping a bore may damage the brain or other underlying soft tissue. To reduce this risk, self-drilling taps for use in cranio-facial procedures generally have a fixed depth. There exists a need for a self-drilling tap having an adjustable length, which may accurately and reliably replace several taps of various fixed lengths.